1 files changed, 165 insertions, 0 deletions
diff --git a/java/com/google/gerrit/server/git/SearchingChangeCacheImpl.java b/java/com/google/gerrit/server/git/SearchingChangeCacheImpl.java
new file mode 100644
index 0000000000..d5e19cc613
--- /dev/null
+++ b/java/com/google/gerrit/server/git/SearchingChangeCacheImpl.java
@@ -0,0 +1,165 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.git;
+
+import com.google.auto.value.AutoValue;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.flogger.FluentLogger;
+import com.google.gerrit.common.Nullable;
+import com.google.gerrit.extensions.events.GitReferenceUpdatedListener;
+import com.google.gerrit.extensions.registration.DynamicSet;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.reviewdb.client.RefNames;
+import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.ReviewerSet;
+import com.google.gerrit.server.cache.CacheModule;
+import com.google.gerrit.server.index.change.ChangeField;
+import com.google.gerrit.server.logging.TraceContext;
+import com.google.gerrit.server.logging.TraceContext.TraceTimer;
+import com.google.gerrit.server.query.change.ChangeData;
+import com.google.gerrit.server.query.change.InternalChangeQuery;
+import com.google.gerrit.server.util.ManualRequestContext;
+import com.google.gerrit.server.util.OneOffRequestContext;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+import com.google.inject.Singleton;
+import com.google.inject.TypeLiteral;
+import com.google.inject.name.Named;
+import com.google.inject.util.Providers;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.ExecutionException;
+
+@Singleton
+public class SearchingChangeCacheImpl implements GitReferenceUpdatedListener {
+  private static final FluentLogger logger = FluentLogger.forEnclosingClass();
+
+  static final String ID_CACHE = "changes";
+
+  public static class Module extends CacheModule {
+    private final boolean slave;
+
+    public Module() {
+      this(false);
+    }
+
+    public Module(boolean slave) {
+      this.slave = slave;
+    }
+
+    @Override
+    protected void configure() {
+      if (slave) {
+        bind(SearchingChangeCacheImpl.class)
+            .toProvider(Providers.<SearchingChangeCacheImpl>of(null));
+      } else {
+        cache(ID_CACHE, Project.NameKey.class, new TypeLiteral<List<CachedChange>>() {})
+            .maximumWeight(0)
+            .loader(Loader.class);
+
+        bind(SearchingChangeCacheImpl.class);
+        DynamicSet.bind(binder(), GitReferenceUpdatedListener.class)
+            .to(SearchingChangeCacheImpl.class);
+      }
+    }
+  }
+
+  @AutoValue
+  abstract static class CachedChange {
+    // Subset of fields in ChangeData, specifically fields needed to serve
+    // VisibleRefFilter without touching the database. More can be added as
+    // necessary.
+    abstract Change change();
+
+    @Nullable
+    abstract ReviewerSet reviewers();
+  }
+
+  private final LoadingCache<Project.NameKey, List<CachedChange>> cache;
+  private final ChangeData.Factory changeDataFactory;
+
+  @Inject
+  SearchingChangeCacheImpl(
+      @Named(ID_CACHE) LoadingCache<Project.NameKey, List<CachedChange>> cache,
+      ChangeData.Factory changeDataFactory) {
+    this.cache = cache;
+    this.changeDataFactory = changeDataFactory;
+  }
+
+  /**
+   * Read changes for the project from the secondary index.
+   *
+   * <p>Returned changes only include the {@code Change} object (with id, branch) and the reviewers.
+   * Additional stored fields are not loaded from the index.
+   *
+   * @param db database handle to populate missing change data (probably unused).
+   * @param project project to read.
+   * @return list of known changes; empty if no changes.
+   */
+  public List<ChangeData> getChangeData(ReviewDb db, Project.NameKey project) {
+    try {
+      List<CachedChange> cached = cache.get(project);
+      List<ChangeData> cds = new ArrayList<>(cached.size());
+      for (CachedChange cc : cached) {
+        ChangeData cd = changeDataFactory.create(db, cc.change());
+        cd.setReviewers(cc.reviewers());
+        cds.add(cd);
+      }
+      return Collections.unmodifiableList(cds);
+    } catch (ExecutionException e) {
+      logger.atWarning().withCause(e).log("Cannot fetch changes for %s", project);
+      return Collections.emptyList();
+    }
+  }
+
+  @Override
+  public void onGitReferenceUpdated(GitReferenceUpdatedListener.Event event) {
+    if (event.getRefName().startsWith(RefNames.REFS_CHANGES)) {
+      cache.invalidate(new Project.NameKey(event.getProjectName()));
+    }
+  }
+
+  static class Loader extends CacheLoader<Project.NameKey, List<CachedChange>> {
+    private final OneOffRequestContext requestContext;
+    private final Provider<InternalChangeQuery> queryProvider;
+
+    @Inject
+    Loader(OneOffRequestContext requestContext, Provider<InternalChangeQuery> queryProvider) {
+      this.requestContext = requestContext;
+      this.queryProvider = queryProvider;
+    }
+
+    @Override
+    public List<CachedChange> load(Project.NameKey key) throws Exception {
+      try (TraceTimer timer = TraceContext.newTimer("Loading changes of project %s", key);
+          ManualRequestContext ctx = requestContext.open()) {
+        List<ChangeData> cds =
+            queryProvider
+                .get()
+                .setRequestedFields(ChangeField.CHANGE, ChangeField.REVIEWER)
+                .byProject(key);
+        List<CachedChange> result = new ArrayList<>(cds.size());
+        for (ChangeData cd : cds) {
+          result.add(
+              new AutoValue_SearchingChangeCacheImpl_CachedChange(cd.change(), cd.getReviewers()));
+        }
+        return Collections.unmodifiableList(result);
+      }
+    }
+  }
+}